* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
}

.screen {
    display: none;
    width: 100%;
}

.screen.active {
    display: block;
}

/* Login Screen Styles */
.login-container {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    min-height: 100vh;
    padding: 20px;
}

.login-container h1 {
    color: white;
    margin-bottom: 30px;
    font-size: 2.5em;
    text-shadow: 2px 2px 4px rgba(0, 0, 0, 0.2);
}

.login-box {
    background: white;
    padding: 40px;
    border-radius: 15px;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.3);
    width: 100%;
    max-width: 400px;
}

.login-box h2 {
    text-align: center;
    margin-bottom: 25px;
    color: #667eea;
}

#authForm input {
    width: 100%;
    padding: 12px;
    margin-bottom: 15px;
    border: 2px solid #e0e0e0;
    border-radius: 8px;
    font-size: 16px;
    transition: border-color 0.3s;
}

#authForm input:focus {
    outline: none;
    border-color: #667eea;
}

#authButton {
    width: 100%;
    padding: 12px;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    border: none;
    border-radius: 8px;
    font-size: 16px;
    font-weight: bold;
    cursor: pointer;
    transition: transform 0.2s;
}

#authButton:hover {
    transform: translateY(-2px);
}

.toggle-auth {
    text-align: center;
    margin-top: 20px;
    color: #666;
}

.toggle-auth a {
    color: #667eea;
    text-decoration: none;
    font-weight: bold;
}

/* App Screen Styles */
.app-container {
    max-width: 800px;
    margin: 20px auto;
    background: white;
    border-radius: 15px;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.3);
    padding: 30px;
}

header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 30px;
    padding-bottom: 20px;
    border-bottom: 2px solid #e0e0e0;
}

header h1 {
    color: #667eea;
}

.user-info {
    display: flex;
    align-items: center;
    gap: 15px;
}

.user-info span {
    color: #666;
    font-weight: bold;
}

.btn-logout {
    padding: 8px 16px;
    background: #ff6b6b;
    color: white;
    border: none;
    border-radius: 6px;
    cursor: pointer;
    font-weight: bold;
    transition: background 0.3s;
}

.btn-logout:hover {
    background: #ff5252;
}

/* Task Input Section */
.task-input-section {
    display: flex;
    gap: 10px;
    margin-bottom: 20px;
}

#taskInput {
    flex: 1;
    padding: 12px;
    border: 2px solid #e0e0e0;
    border-radius: 8px;
    font-size: 16px;
}

#taskInput:focus {
    outline: none;
    border-color: #667eea;
}

#assignTo {
    padding: 12px;
    border: 2px solid #e0e0e0;
    border-radius: 8px;
    font-size: 16px;
    cursor: pointer;
}

.btn-add {
    padding: 12px 24px;
    background: #667eea;
    color: white;
    border: none;
    border-radius: 8px;
    font-weight: bold;
    cursor: pointer;
    transition: background 0.3s;
}

.btn-add:hover {
    background: #5568d3;
}

/* Filter Section */
.filter-section {
    display: flex;
    gap: 10px;
    margin-bottom: 20px;
    flex-wrap: wrap;
}

.filter-btn {
    padding: 8px 16px;
    background: #f0f0f0;
    border: 2px solid transparent;
    border-radius: 6px;
    cursor: pointer;
    font-weight: bold;
    transition: all 0.3s;
}

.filter-btn:hover {
    background: #e0e0e0;
}

.filter-btn.active {
    background: #667eea;
    color: white;
}

/* Task List */
.task-list {
    display: flex;
    flex-direction: column;
    gap: 10px;
}

.task-item {
    display: flex;
    align-items: center;
    gap: 15px;
    padding: 15px;
    background: #f9f9f9;
    border-radius: 8px;
    border-left: 4px solid #667eea;
    transition: all 0.3s;
}

.task-item:hover {
    background: #f0f0f0;
    transform: translateX(5px);
}

.task-item.completed {
    opacity: 0.6;
    border-left-color: #4caf50;
}

.task-checkbox {
    width: 20px;
    height: 20px;
    cursor: pointer;
}

.task-content {
    flex: 1;
}

.task-title {
    font-size: 16px;
    color: #333;
}

.task-item.completed .task-title {
    text-decoration: line-through;
    color: #999;
}

.task-meta {
    font-size: 12px;
    color: #999;
    margin-top: 5px;
}

.task-actions {
    display: flex;
    gap: 10px;
}

.btn-edit,
.btn-delete {
    padding: 6px 12px;
    border: none;
    border-radius: 4px;
    cursor: pointer;
    font-weight: bold;
    transition: background 0.3s;
}

.btn-edit {
    background: #ffc107;
    color: white;
}

.btn-edit:hover {
    background: #ffb300;
}

.btn-delete {
    background: #ff6b6b;
    color: white;
}

.btn-delete:hover {
    background: #ff5252;
}

.empty-state {
    text-align: center;
    padding: 40px;
    color: #999;
}

/* Responsive Design */
@media (max-width: 768px) {
    .app-container {
        margin: 10px;
        padding: 20px;
    }

    .task-input-section {
        flex-direction: column;
    }

    header {
        flex-direction: column;
        gap: 15px;
        align-items: flex-start;
    }

    .filter-section {
        gap: 5px;
    }

    .filter-btn {
        font-size: 14px;
        padding: 6px 12px;
    }
}